I think guzmand19 hit the nail on the "head"
In one of my leagues, we have a medium-light oil pattern. My 1st year in, I brought a ball with a ton of back end and was leaving several pocket 7-10's.
Now there is only one bowler there with a 200+ avg who leaves them regularly. The funny thing is, someone told me he was buying a new ball, so I figured he was trying to correct this problem. However, when he showed up to bowl, I saw that his new ball was a Vertigo! Of course, this didn't cure his problem.